Recent theoretical work has established “no-go” results for successfully imitating an expert that has access to more information [1]}, [2]}. The core of their arguments is that without seeing some feature that influences expert behavior but is not echoed elsewhere in the state, the learner might not be able to properly ground the expert actions in the observed state. In causal inference terms, this hidden information acts as an unobserved confounder which prevents identification of the desired treatment effect (the expert action). Despite these results, impressive empirical successes have been achieved even when the learner has a more impoverished state representation than the expert.
